Conventionally, an arrangement in which for the purpose of increasing the flow rate of exhaust gas of a silencer and reducing the exhaust resistance, two outlet pipes (dual type) for exhaust gas to flow are provided is already known; for example, an exhaust silencing device disclosed in Patent Document 1 below includes a silencer main body (silencer), an inlet pipe (exhaust pipe) 2 that has at the downstream end an opening portion opening within the silencer main body and that guides exhaust gas from an engine to the interior of the silencer main body, and two outlet pipes, that is, a short outlet pipe (tailpipe) 11 and long outlet pipe (tailpipe) 12 that have at the upstream end an opening portion opening within the silencer main body and that discharge the exhaust gas within the silencer main body to the outside of the silencer main body, an opening portion 12a of the long outlet pipe 12 being positioned above an opening portion 11a of the short outlet pipe 11, and condensed water that builds up at the bottom of the silencer accompanying the exhaust gas being cooled is discharged outside mainly via the short outlet pipe, thereby reducing the flow of condensed water into the long outlet pipe.
In the above arrangement of Patent Document 1, if the amount of condensed water within the long outlet pipe increased, since there is a possibility that the output of the engine would decrease, the silencing effect would decrease, and the outlet pipe would be blocked due to freezing of condensed water in winter, condensed water flowing into the long outlet pipe has to be reduced.